1. Field of the Invention
The present invention relates to a cigarette, and more particularly, to a cigarette which is excellent in an appearance-sustaining ability.
2. Description of the Related Art
It is most important that a cigarette is excellent in flavor of smoking in the quality thereof; however, other matters on the quality are also important. For instance, it is desirable that a cigarette is beautiful in its appearance and is manufactured at low costs. In order to satisfy the conflicting requirement for manufacturing cigarettes having a high quality at low costs, various cigarette manufacturing techniques have conventionally been invented for practical applications.
To give an example relating to manufacture of cut tobacco, U.S. Pat. No. 3,524,452 discloses "process for increasing the filling capacity of tobacco" in which the moisture content of tobacco is adjusted, and the tobacco is wetted with inert organic liquid. Further, the liquid is quickly vaporized by passing the stream of tobacco in contact with a stream of heated gas, thereby expanding the tobacco. This process makes it possible to provide cigarettes including tension in its paper web even if a filling amount of tobacco is reduced.
It is also known to use a mixture of midrib shreds and leaf-meat shreds as tobacco shreds so as to effectively utilize tobacco leaves, the midrib shreds being obtained by rolling and shredding midrib portions (veins, secondary veins, etc.) of the tobacco leaves, which are separated from leaf-meat portions of the tobacco leaves and to which water is added (see Japanese Patent Publication No. 46-8440, etc.).
Moreover, various improvements have been made in cigarette manufacturing machines. In general, an improved cigarette manufacturing machine comprises a cut tobacco supply section, a wrapping section, and a cutting section. The wrapping section is supplied with a paper web, which travels in one direction in the wrapping section. The supply section feeds cut tobacco onto the paper web at the starting end of the wrapping section. As the cut tobacco, along with the paper web, passes through the wrapping section, it is wrapped in the web to form a continuous cigarette rod. Thereafter, the formed cigarette rod is delivered from the wrapping section to the cutting section. As it passes through the cutting section, the cigarette rod is cut into individual cigarettes with a predetermined length.
An example of the supply section of a cigarette manufacturing machine is disclosed in Japanese Patent Publication No. 40-14560. This conventional supply section is provided with an endless suction band, that is, a tobacco band as it is called. The tobacco band extends toward the wrapping section, and has one surface formed as a suction surface. Cut tobacco is attracted in a layer to the suction surface of the tobacco band. As the tobacco band travels, the cut tobacco layer is transported toward the wrapping section. The tobacco layer is released from the attraction at the starting end of the wrapping section, whereupon the cut tobacco is continuously fed from the tobacco band onto the paper web at the wrapping section.
Specifically, as shown in FIG. 1, tobacco shreds K.sub.T are moved toward a tobacco band 1 together with the air flow in the direction shown by an arrow C while being directed to various orientations in the air flow. Then, the tobacco shred K.sub.T, which is sent by air with such an orientation that the axis of the tobacco shred crosses at right angles to the tobacco band 1 traveling in the direction shown by an arrow D, is attracted onto the tobacco band 1 at its one end by suction, as shown in FIG. 2. Thereafter, the entirety of this tobacco shred is attracted onto the tobacco band by suction, as shown in FIG. 3. On the other hand, in the case of another tobacco shred K.sub.T, which is sent by air with such an orientation that the axis of the tobacco shred extends in parallel with the tobacco band 1, the whole of the tobacco shred is almost simultaneously attracted onto the tobacco band by suction (FIG. 2).
As a result, as shown in FIG. 4, a cut tobacco layer T.sub.L is formed of individual tobacco shreds K.sub.T which are stacked on a suction surface of a tobacco band 1. Thereafter, the tobacco shred K.sub.T of the layer is fed onto a paper web at the wrapping section.
As the paper web 2, along with the tobacco shreds K.sub.T, passes through the wrapping section, it is first bent in the shape of a U, as shown in FIG. 5. Thereafter, both sides of the U-shaped web 2 are successively bent in a circular arc, whereupon a continuous cigarette rod is formed.
FIG. 6 shows a filter cigarette which is formed of a cigarette obtained by cutting the cigarette rod and a filter connected to the cigarette. FIG. 7 shows an end face of the filter cigarette. In FIGS. 6 and 7, reference numeral 3 denotes a lap portion which combines both side edges of the paper web 2.
As is evident from the foregoing description of the process for forming the cigarette rod, the tobacco shreds K.sub.T on the paper web 2 are kept substantially in layers even though they are wrapped in the web 2. Also, most of the tobacco shreds K.sub.T in the cigarette are oriented in one direction.
More specifically, most of the tobacco shreds K.sub.T are obtained by cutting tobacco leaves. As shown in the exaggerated view of FIG. 8, these tobacco shreds K.sub.T are rectangular fragments each having a pair of long sides K.sub.le with a length L and a pair of short sides K.sub.se with a length S.
Most of these fragments K.sub.T tend to be attracted to the tobacco band 1 with an orientation such that their respective long sides K.sub.le extend along the traveling direction of the tobacco band 1. As shown in FIGS. 4 through 7, therefore, most of the stacked fragments K.sub.T are oriented so that their short sides K.sub.se extend parallel to the cross section of the tobacco band 1 or the paper web 2, and their long sides K.sub.le at right angles to the cross section.
As viewed from the end face of the cigarette shown in FIG. 7, most of the individual tobacco shreds K.sub.T are wrapped in the paper web 2 in a manner such that their short sides K.sub.se extend parallel to the lap portion 3 of the cigarette.
As described above, most of tobacco shreds K.sub.T are attracted onto the tobacco band 1 by suction so that their long sides K.sub.le are positioned along the traveling direction of the tobacco band 1. During the movement of the tobacco shreds K.sub.T toward the tobacco band 1 with the air flow, however, the tobacco shreds K.sub.T can be directed to various orientations; for this reason, all of long sides K.sub.le of the tobacco shreds K.sub.T are not always positioned parallel to the traveling direction of the tobacco band 1. Nevertheless, in the case where the supply of tobacco shreds and the formation of cigarette rods are performed in the aforementioned manner, the tobacco shreds K.sub.T are arranged at least so that their leaf surfaces K.sub.F extend along the axis of cigarette (see FIG. 9).
The tobacco shreds K.sub.T more easily undergo elastic deformation when their opposite leaf surfaces K.sub.F (see FIG. 8) are subjected to external forces than when their long and short sides K.sub.le and K.sub.se receive external forces.
Thus, in the case where the tobacco shreds K.sub.T in the cigarette take the form of a layer as described above, in other words, in the case where the tobacco shreds K.sub.T are arranged so that their leaf surfaces K.sub.F extend along the axis of cigarette, if the cigarette is subjected to external forces in the direction A--A, as shown in FIG. 7, these forces act on the opposite leaf surfaces of most of the tobacco shreds K.sub.T in the cigarette, so that the outer peripheral surface of the cigarette is easily deformed.
If the cigarette is subjected to external forces in the direction B--B. On the other hand, these forces act on the long sides K.sub.le of most of the tobacco shreds K.sub.T in the cigarette, so that the outer peripheral surface of the cigarette cannot be easily deformed.
As described above, in the cigarette whose hardness is higher in the direction B--B than in the direction A--A, there is irregularity of hardness in the circumferential direction of the cigarette. In this case, the cigarette is easily deformed. More specifically, when a smoker nips the cigarette between his or her fingers, as shown in FIG. 10, if a nipping force acts on the leaf surfaces of the tobacco shreds K.sub.T, cockles appear in the paper web 2, so that the cigarette is injured in its appearance. Further, if impact exerting in the axial direction of the cigarette acts on the cigarette, the tobacco shreds at the tip of cigarette retract inwardly to form a depression. This also injures the appearance of the cigarette.
In order to maintain a preferable appearance of cigarette, the cigarette may be formed to have a suitable hardness so that the cigarette has an ability of self-sustaining its appearance. Generally, the higher the filling density of tobacco shreds is made, the harder the cigarette becomes. Thus, it is possible to manufacture a cigarette which has a suitable hardness and an excellent ability to maintain its appearance by adjusting the filling density of cut tobacco. However, since cigarettes must be provided at low costs even if the cigarettes have whatever high quality, an increase of the filling density of cut tobacco to a considerable extent causes costs to rise because cut tobacco is high-priced, and is hence impractical.